In modern surgical practice, many procedures which formerly required large incisions have been supplanted by techniques employing microsurgical tools. Such tools are generally introduced to the surgical site through small incisions which create far less surgical trauma, and hasten healing and recovery.
A significant aspect of many of the newly developed surgical tools is the use of vacuum aspiration to draw tissue into a power driven cutting head. It is well recognized that the rate of tissue cutting and removal is related to the rate of operation of the cutting head, and also to the vacuum level applied to the aspiration port associated with the cutting head. Thus it is clear that precise control of the vacuum level is essential to successful operation of this type of surgical instrument.
Until recently it was standard practice to have tubing and hoses extending to the cutting instrument to provide aspiration, irrigation fluid, and motive power to the cutting head. The tubing generally was manually secured through pinch valves on the console of a surgical instrument control machine to provide control of the irrigation and aspiration functions. However, this procedure was subject to human error in the placement of the proper tubing in the proper pinch valve, and it was also possible for the tubing to become dislodged accidentally. The outcome of such errors can be catastrophic during surgery.
One means for overcoming this problem is disclosed in U.S. Pat. No. 4,475,904, issued Oct. 9, 1984 to Carl C. T. Wang. This device provided a pair of aspiration containers in a cassette housing, one container having a significantly smaller volume than the other. The containers are connected by tubing affixed to an outer wall of the cassette, and valves extending from the console of the surgical control machine are disposed to engage the tubing automatically when the cassette is secured to the machine. Also, the vacuum connections to the cassette are engaged automatically upon installation of the cassette. Thus the human error aspect is alleviated. More significantly, the assembly provides the fast response to changes in vacuum associated with a small volume while also providing a large storage capacity.
However, pinch valves mounted on the exterior of a machine exhibit intrinsic reliability problems, such as clogging by foreign matter, sticking, and the like. Furthermore, the tubing itself must be extremely resilient to expand quickly when the pinch valves open, so that the response time of the overall assembly does not lag. If a tubing section remains pinched by a valve for a long period of time, plastic deformation may occur, and the flow channel will be constricted, thus altering the operating characteristics of the surgical tool. Temperature changes may also affect the resilience of the tubing.
It is additionally problematic that many times surgery requires contemporary use of different types of surgical instruments. As previously discussed, aspiration, irrigation, and mode of power for a cutting tool require connection to different sources. Use of tubing or hoses is susceptible to problems, as previously discussed, which is compounded by the different sources and types of tools. It would therefore be advantageous to have an integrated control center and conduit for the different sources and tools.